Staphylococcus is the most common cause of infections worldwide. The pathogen persists asymptomatically on human skin from which it may spread to ocular tissues and cause corneal infection. When this happens, corneal bacterial keratitis can occur, and if not treated effectively, it may lead to blindness. Multi Drug Resistant (MDR) variants of S. aureus (Sa) are increasingly prevalent and are of major clinical concern, as the arsenal of effective antibiotics available for treatment is becoming depleted. The problem of antibiotic resistance is compounded by the ability of Sa to grow, not only in its familiar planktonc form, but also in the form of compact biofilms against which current antibiotics have limited effect. This creates a need to discover new and effective modalities against MDR pathogens. But it also creates a commercial opportunity, particularly if it is possible to reduce the likelihod that MDR pathogens will become resistant to these modalities. In this phase I STTR proposal, AmebaGone, LLC, in collaboration with the academic partner at the School of Medicine and Public Health of University of Wisconsin-Madison, will carry out proof-of principle experiments to test whether treating bacterial keratitis with Dictyostelid Cells (DC) can mitigate ocular Sa infections. DC are microscopic unicellular professional phagocytes of group Conosa that devour bacteria as their normal food source. DC can engulf and digest bacteria at a prodigious rate; and they exponentially multiply, until the bacterial prey is gone. Only when the supply of the surface exposed bacteria is large and the oxygen is abundant they become multi-cellular and differentiate into dormant spores. Genomic analyses of these organisms suggest that DC were among the earliest multi-cellular organisms to arrive on dry land. Because the sporulation cannot occur when DC feed on submerged bacteria; their evolutionary split from the aquatic amoebic cells (group Lobosa), some of which are pathogenic, had occurred over billion years ago. Humans and animals encounter DC in soil worldwide - with no adverse consequences. It is highly significant to this project that AmebaGone, LLC, has already acquired several Dictyostelid strains and has shown that these organisms can kill planktonic and biofilm-encased S. aureus - MRSA (USA300). These strains are samplings from a large archive of over 3,000 natural isolates of DC from diverse locations. Our aims are: (1) Screen a preselected group of DC for their ability to feed on planktonic and biofilm-encased cells of S. aureus 8325-4, a common pathogen of ocular tissues, (2) Determine the toxicity of DC when applied topically to the mouse cornea and determine the residence time of DC on the cornea following a single application, and, (3) Test the efficacy of DC in treating murine corneal infections with the strain of S. aureus If DC have no adverse effects and are efficacious against S. aureus in the ocular tissues of the mouse, the treatment will be tested in Phase II in a rabbit model of keratitis. The issued patents, the company owns, are to protect commercialization of DC as therapeutics in medicine and agriculture.